Implantable stimulation devices are devices that generate and deliver electrical stimuli to body nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and deep brain stimulators to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder sublaxation, etc. The present invention may find applicability in all such applications, although the description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. No. 6,516,227, which is incorporated herein by reference in its entirety.
Spinal cord stimulation is a well-accepted clinical method for reducing pain in certain populations of patients. As shown in FIGS. 1A and 1B, an SCS system typically includes an Implantable Pulse Generator (IPG) 100, which includes a biocompatible case 130 formed of titanium, for example. The case 130 typically holds the circuitry and power source or battery necessary for the IPG 100 to function, although IPGs can also be powered via an external RF energy source and without a battery. The IPG 100 is coupled to electrodes 106 via one or more electrode leads (two such leads 102 and 104 are shown), such that the electrodes 106 form an electrode array 110. The electrodes 106 are carried on a flexible body 108, which also houses the individual signal wires 112 and 114 coupled to each electrode. In the illustrated embodiment, there are 16 electrodes on lead 102, labeled E1-E16, and sixteen electrodes on lead 104, labeled E17-E32, although the number of leads and electrodes is application specific and therefore can vary.
Patients with implanted neurostimulators must have a means for communicating with and controlling their implant. Typically, different stimulation settings are needed to provide complete pain coverage throughout the day. The patient uses an external (remote) controller to adjust the stimulator output to obtain the best therapy. Different therapy settings may be required when the patient is sleeping, standing, sitting, or driving. Some settings may be saved as programs and may be selected by the patient using the external controller. Common uses of the external controller are to increase or decrease the strength of stimulation, to select different areas of the body to be stimulated, and to shut off and turn on stimulation.
FIG. 2 shows portions of an IPG system in cross section, including the IPG 100 and an external controller 200. The IPG 100 typically includes an electronic substrate assembly 214 including a printed circuit board (PCB) 216, along with various electronic components 220, such as a microcontroller, integrated circuits, and capacitors mounted to the PCB 216. Two coils are generally present in the IPG 100: a telemetry coil 213 used to transmit/receive data to/from the external controller 200, and a charging coil 218 for charging or recharging the IPG's power source or battery 226 using an external charger (not shown). The telemetry coil 213 can be mounted within the header connector 236 as shown.
As just noted, an external controller 200, typically a hand-held device, is used to wirelessly send data to and receive data from the IPG 100. For example, the external controller 200 can send programming data to the IPG 100 to set the therapy the IPG 100 will provide to the patient. In addition, the external controller 200 can act as a receiver of data from the IPG 100, receiving various data reporting on the IPG's status.
The communication of data to and from the external controller 200 occurs via magnetic inductive coupling. When data is to be sent from the external controller 200 to the IPG 100 for example, coil 217 is energized with an alternating current (AC). Such energizing of the coil 217 to transfer data can occur using a Frequency Shift Keying (FSK) communication technique for example, such as disclosed in U.S. Patent Publication 2009/0024179. Energizing the coil 217 generates a magnetic field, which in turn induces a current in the IPG's telemetry coil 213, which current can then be demodulated to recover the original data. Such inductive communications occur transcutaneously, i.e., through the patient's tissue 225, making it particularly useful in a medical implantable device system.
External controllers 200 available today are developed by medical device manufacturers, and such development requires substantial investments. For one, care has to be taken by the developer to create a user interface for the external controller 200 that patients and clinicians will like and find easy to use. As such, external controllers 200 are typically designed with user interfaces having displays, buttons, speakers, etc. Development of such a user interface is expensive for the medical device manufacturer, and is not easy to change once displayed.